Sina, the company that owns China’s über-popular Twitter-like service Weibo, has had two key licences withdrawn by Beijing in retaliation for allegedly allowing the publication of articles and videos containing pornographic content.

A missive from the National Office Against Pornographic and Illegal Publications seen by Xinhua claimed that 20 articles and four videos posted to Sina.com had broken anti-porn laws and as a result the government had revoked the firm’s internet publishing and audio and video publishing licences.

The firm has been hit with a “large number of fines”, some staff have been detained and some local reports claim Sina has already shuttered its online book site for the time being.

The statement apparently said Sina had not learned its lesson after being punished twice last year for publishing banned content and was “turning a cold shoulder on social responsibility”.

“[The site] overstepped the red line of law... and it must be punished in accordance with laws and regulations," it added, according to Xinhua.

For its part, Sina has issued a grovelling apology, promising to “obey the punishment without passing the buck”.

The harsh treatment of one of China’s biggest internet companies is part of a renewed crackdown on "lewd" or pornographic content instigated by president Xi Jinping, and can be seen as a major warning to other big names to police content on their platforms more carefully.

Weibo – which boasts 600 million registered users, less than half of whom are active – recently filed for a $500m IPO in the US.

Unsurprisingly, the news of its punishment has hit parent company Sina’s stock price hard, with shares plummeting more than 7 per cent on Thursday, according to Reuters.

The firm not only has an increasing self-censorship burden to manage but is also losing the battle for hearts and minds, especially of younger Chinese, to newer services like WeChat (Weixin). ®